Bearing alloy



Patented June 14, 1949 BEARING ALLOY Harold Y. Hunsicker, Cleveland, andLouis Walter Kempf, Shaker Heights, Ohio, assignors to Alumlnu'm Companyof America, Pittsburgh, Pa, a corporation of Pennsylvania Ne Drawing.Application N ovember 14, 1945, Serial No. 628,659

5 Claims.

This invention relates to a metallic composi I tion to be used as abearing and anti-friction material and the bearings made from thiscomposition. The object of the invention is to improve the presentaluminum alloy bearings now in use in the trade and to provide analuminum alloy bearing characterized by superior bearing andwear-resisting properties and ability to carry a relatively high loadunder conditions of constant loading or under conditions of repeatedimpact loading. A further object of this invention is to provide abearing material which has good resistance at normal or elevatedtemperatures to the corrosive agents present in lubricating oils or inthe decomposition products of such oils, which are harmful to bearings.It is another object of this invention to provide such a bearingmaterial which may, in addition, be readily machined and finished to avery smooth surface which will form a maximum of true bearing area andpromote uniformity of bearing pressure distribution.

The alloyed bearing material which is the subject of this invention iscomposed principally of aluminum. That metal is available in eitherprimary form or in the form of secondary or scrap metal. Either form maybe used in this new bearing material, but when secondary or scrap metalis used, impurities such as iron, manganese,

nickel, magnesium, zinc, titanium and chromium should be limited to apermissible amount of less than about 2 per cent by weight of totalmaterial, and no single such impurity should preferably be permitted inamounts in excess of about 1 per cent. Apart from aluminum. the newbearing alloy consists of 5 to 25 per cent by weight of tin, 5 to 12 percent by weight of silicon and 0.5 to 10 per cent by weight of silver.Preferably, and for best results, the tin should be present in amount inexcess of the amount of silicon and the silver should exceed about 2.5per cent by weight. We have found that silver stabilizes the siliconparticles which are distributed through the aluminum matrix of thisalloy and does so without impairing or disturbing the important andimproved anti-friction and abrasion resisting properties of the bearingmaterials. If desired, a portion of the tin may be replaced by a metalselected from the group consisting of a lead and cadmium, which areother low melting constituents often used in bearing alloys. However, ifequivalency is to be maintained, such replacement should not take placeto an extent which would be greater than 30 per cent of the total amountof tin, lead and cadmium in the alloy or greater than 2 per cent byweight of the total alloy, whichever amount is the lesser.

For bearings which are subjected to severe alternating, rotating orpulsating loads we prefer to use the alloy as described containing notmore than about 15 per cent by Weight of the lowmelting constituent,which is composed principally of tin. For bearings which are subjectedto an essentially constant and unidirectional load or relatively lightalternating, rotating or pulsating loads, a higher concentration of thelowmelting constituent, about 15 to 25 per cent, may be employed in thealloy providing the advantage of further improvement in theanti-friction qualities.

The aluminum. alloy just described may be used as a bearing material ineither cast or wrought form, but when the alloy is to be worked into theform of sheet, it is desirable that the alloying elements be present inamounts which lie in the lower portions of the ranges of those elementsabove set forth.

By proper heat treatments, improved bearing characteristics as well asdimensional stability may be imparted to bearings made of our novelmaterial. Where stabilization of dimensions is the reason for the heattreatment, a heating for 8 to 12 hours at temperatures of about 350 to440 degrees F. will prove satisfactory. Such heat treatment will alsoincrease strength and hardness tosome extent. Where it is desirable toimprove machining characteristics, bearing qualities and wear resistanceof the material we prefer to use a heat treatment which comprisesheating the bearing material for 8 to 12 hours at temperatures of 850 to950 degrees F., then cooling the thus heated material as by quenching inwater, air or other coolant, and thereafter reheating the material to350 to 450 degrees F. for a period of 8 to 12 hours. The times andtemperatures given are merely exemplary of heat treatment methods whichmay be used to improve the bearings and are the heat treatments which wehave found to be best suited to this purpose. Other heating steps forother times and at temperatures which do not exceed temperatures atwhich undue melting of the bearing material would be caused may, ifdesired, be used.

Tests of bearings made of the alloys above described have demonstratedthat said bearings are superior to those aluminum alloy bearings in useprior to this invention.

We claim:

1. A hearing composed of an alloy consisting of 5 to 25 per cent byweight of tin, 5 to 12 per cent by weight of silicon and 0.5 to 10 percent by weight of silver, the balance being principally aluminum withimpurities not exceeding 2 per cent by weight of the alloy.

2. A bearing composed of an alloy consisting of 5 to 25 per cent byweight of tin, 5 to 12 per cent by Weight of silicon and 0.5 to per centby weight of silver, the balance being principally aluminum withimpurities not exceeding 2 per cent by weight of the alloy, the amountof tin being in excess of the amount of silicon.

3. A bearing composed of an alloy consisting of 5 to 25 per cent byweight of tin, 5 to 12 per cent by weight of silicon and 2.5 to 10 percent by weight of silver, the balance being principally aluminum withimpurities not exceeding 2 per cent by weight of the alloy.

4. An anti-friction bearing alloy consisting of 5 to 25 per cent byweight of tin, 5 to 12 per cent by weight of silicon and 0.5 to 10 percent by 4 weight of silver, the balance being principally aluminum withimpurities not exceeding 2 per cent by weight of the alloy.

5. An anti-friction bearing alloy consisting of 5 to per cent by weightof tin, 5 to 12 per cent by weight of silicon and 0.5 to 10 per cent byweight of silver, the balance being principally aluminum with impuritiesnot exceeding 2 per cent by weight of the alloy, the amount of tin beingin excess of the amount of silicon.

HAROLD Y. I-IUNSICKER. LOUIS WALTER KEMPF.

REFERENCES CITED FOREIGN PATENTS Countw Date Germany Feb. 18, 1928Number

